This invention relates to sliding fasteners, and more particularly to zippers having interlocking coupling elements alternately attached to separate stringers.
While the major function of a zipper assembly is mechanicalxe2x80x94to reversibly couple two generally planar items together, aesthetic considerations also arise which may dictate when and how a zipper may be use in a given application. The aesthetic considerations are aural, tactile and visual. The present invention alters the visual aspect of the zipper assembly to provide a less mechanical appearance, while at the same time generally altering the sound and feel of the zipper when it is opened and closed.
The present invention provides for a zipper assembly comprising two stringers, each stringer having a row of coupling elements having a plurality of different coupling element spacings, and at least one stringer having a plurality of different coupling element widths.
A xe2x80x9ccoupling elementxe2x80x9d is herein defined as a substantially rigid projection arrayed along a strip and/or cord in a spaced fashion with other substantially rigid projections to form a stringer, the rigid projection having surface geometry for mechanical interlocking with mating surface geometry of two adjacent projections on a mating stringer. A xe2x80x9cstringerxe2x80x9d is defined as a flexible zipper half having a linear array of coupling elements, capable of coupling to a second linear array of coupling elements (e.g., by means of a slider, whereby the coupling elements on the stringers are temporarily rotated to allow them to be interleaved, then straightened to geometrically interlock them with adjacent mating coupling elements). A xe2x80x9csliderxe2x80x9d is defined as a moveable element having a pair of channels for reversibly directing the two arrays of non-interlocked coupling elements of the stringers through a curved coupling path and into a parallel interlocked relationship. The use and construction of sliders is well known to those versed in the art. A xe2x80x9czipperxe2x80x9d is defined as two mating stringers, while a xe2x80x9czipper assemblyxe2x80x9d is defined as a zipper comprising a slider. The xe2x80x9cpitch linexe2x80x9d of the zipper is defined as the line that bisects the coupling elements of a closed zipper. The xe2x80x9ccoupling element spacingxe2x80x9d, or xe2x80x9cpitchxe2x80x9d, is defined as the distance along the pitch line and between the center of a stringer coupling element to the center of the next adjacent coupling element on the same stringer. The xe2x80x9cwidthxe2x80x9d of a coupling element is measured along the pitch line of the zipper, and is equal to one half of the coupling element spacing of a closed zipper having identical coupling elements. The xe2x80x9cpitch sequencexe2x80x9d of the zipper is defined as the consecutive listing of the coupling element widths of the zipper when closed.
In a preferred embodiment, the second stringer pitch sequence has a reversed relationship to the first stringer pitch sequence, to produce a palindromic zipper. For instance, if the first stringer pitch sequence is ABBAAA, where xe2x80x9cAxe2x80x9d and xe2x80x9cBxe2x80x9d represent short and long coupling elements, respectively, then the second stringer pitch sequence would be aaabba, and the assembled zipper pitch sequence would be AaBaBaAbAbAa. (In this example, upper and lower case are used only to distinguish the stringers on which the coupling elements reside.) The first coupling element spacing on the first stringer, starting from the left end, would be 1.5 times the xe2x80x9cAxe2x80x9d width plus 0.5 times the xe2x80x9cBxe2x80x9d width; while the second coupling element spacing on this stringer would be the xe2x80x9cAxe2x80x9d width plus the xe2x80x9cBxe2x80x9d width. Using only two coupling element widths, there are a minimum of two and a maximum of five coupling element spacings. If three coupling element widths were used, there would be a maximum of ten coupling element spacings. As may be appreciated, the maximum number of coupling element spacings increases dramatically as the number of coupling element spacings increases.
In another preferred embodiment, a stringer pitch sequence is periodic, e.g., ABABAB, or ABCCABCC. In another embodiment, the sequence may be selected to carry information in coded form, e.g., the stringer coupling element widths or assembled zipper pitch sequences may use a code such as Morse code to spell out a brand name or other information, in order to make counterfeiting of items incorporating the zipper more difficult. In yet other embodiments, the sequence may be non-repeating; the coupling element widths of one stringer may be different from the coupling element widths of the mating stringer; and the number of coupling element widths on one stringer may be different from that of the mating stringer, e.g., one stringer may have only one coupling element width (but a plurality of coupling element spacings) while the mating stringer has two or more coupling element widths. In every embodiment of the present invention, each stringer of a zipper assembly has a plurality of coupling element spacings, and at least one stringer also has a plurality of coupling element widths.
When the zipper is opened or closed, friction and impact of the closure elements within the slide and interaction of the closure elements of one stringer with the closure elements of the mating stringer create noise and vibration that are sensed by the user. The aesthetic character of these effects are dependent in some degree upon the spacing of the closure elements and therefore may be modified and enhanced by suitable choice of spacings provided by the present invention.
It is preferred that coupling element spacings within a stringer vary at least once by at least about one percent, more preferably by at least 5%, and most preferably by at least 10%; and it is more preferred that the coupling element spacings alternate between at least two values at least 5 times, and most preferably at least 10 times.
The coupling elements may be metallic or polymeric, but are preferably generated from thermoplastic materials, e.g., by continuous injection molding on a form wheel and form band. Such a manufacturing method is described in U.S. Pat. No. 4,137,034, the teachings therein entirely incorporated herein by reference. The surface geometry that interlocks a given coupling element with an adjacent coupling element may comprise male and female projections that prevent relative movement in both the plane of zipper and in the direction orthogonal to the plane. Alternatively, mating projections may be used to prevent movement in the zipper plane, with separate projections to prevent motion orthogonal to the plane. End stops can be provided at each end of each stringer.
It is an object of the present invention, therefore, to provide a zipper having improved visual aesthetics.
It is another object of at least one embodiment of the invention to provide a zipper having improved tactile and aural aesthetics when opened and closed.
It is another object of at least one embodiment of the invention to provide a zipper having variable pitch.
It is another object of at least one embodiment of the invention to provide a zipper having information coded in the zipper pitch sequence.